Smooth and effortless tracking of the Alvin ® Track Drafting Machine is accomplished by 14 uniquely designed flat face bearing rollers strategically placed for precise vertical and horizontal movement at any board angle. A comfortably designed palm rest and thumb release allows easy rotation of the protractor head with convenient 15° auto index settings and intermediate lockable fine line adjustment. The 360° protractor head with built-in magnifier is divided into single degrees with 5-minute double vernier permitting angular accuracy to 1/12 of a degree. A double action hinge system allows the head and scales to be tilted vertically from the board surface for a clear working view and also allows the head to sit flat on the board, compensating for any board irregularities. A floating head mechanism positions the protractor above the surface to protect against accidental smearing or tearing of drawing media. An exclusive feature is the positive double shoe braking system with dual lever fingertip operation, precisely controlling and locking both horizontal and vertical movement. Thus, always insuring complete straight lines. Additional features include a one-touch lever to install or dismount the vertical track; and an adjustable vertical track support roller to accommodate both varying board depths and thickness. Each machine comes with a full protective plastic dust cover large enough for both machine and drawing surface. Scales not included.